(a) Field of the Invention
This invention relates to novel derivatives of butanediol represented by the following general formula: ##STR2## wherein R is an alkyl group containing 5-21 carbon atoms or an alkenyl group containing 5-21 carbon atoms with 1-2 unsaturated bonds; the preparation of these compounds, and pharmaceutical compositions containing such compounds. The present invention also contemplates a method of preparing such compounds and the use of such compounds as anti-tumor agents.
(b) Description of the Prior Art
With regard to hitherto known anti-tumor agents, undesirous side-effects such as leucopenia, thrombopenia, alopecia, myelosis, nausea, vomiting and diarrhea have been reported after an administration of these agents. There are certain kinds of so-called "folk medicines" which are believed to be effective for treating patients with tumors and such medicines can be administered for a tolerably long period of time without conspicuously undesirous side-effects. For example, it has been reported that the administration of decoctions obtained from the seeds of Chinese pearl barley increased the lifespan of animals suffering from cancer at the terminal stage [M. Nakayama; The Bulletin of The Japan Surgery Association: Vol. 61, pages 234-246 (1960)] and acetone extractions from the seeds of pearl barley had a growth inhibiting activity against the cells of Ehrlich ascites carcinoma in mice and their active component was identified to be butanediol-2,3-cis-9-hexadecenoyl-3-trans-11-octadecenoate [T. Ukita & A. Tanimura: The Chemical & Pharmaceutical Bulletin; Vol. 9, pages 43-46 and 47-53 (1961)]. Further, it was reported that in the investigation for seeking fat-soluble ingredients in the seeds of pearl barley, the existence of coixenolide was not identified when a diester synthesized from 2,3-butanediol and oleyl chloride was employed as a standard substance. [T. Nagao et al: The abstracts from the lectures published at the 103th general meeting of the Japan Pharmaceutical Association (1983, in Tokyo)].
On the basis of above prior art teachings, investigations have been conducted by the present inventors for obtaining butanediol derivatives which will have a strong antitumor activity but have a low toxicity, and this invention has been achieved as a part of our series of investigations.